Most Notorious Cocktails
I'm going to nominate the Third Degree Burn ...
A shot of (equal amounts of) each, 100 proof Rumpleminz, 100 proof Southern Comfort and Bacardi's 151 Rum. This drink could also probably be mentioned on the "Worst Drink Ever" thread too ... but if you choke it down, pretty soon you forget the taste.
As far as a "class" of drink as notorious ... I'm going to say the "grape juice" class (if you can call it that). Grape juice is the classic "nah, there's not much booze in it" mixer from teen years ... often the mixer for 151.
"Hey! This doesn't taste too bad!" ... uh-huh.